When printing barcodes, it is important to insure that each barcode can be read (i.e., scanned) by various barcode scanners in a wide range of scanning environments. As a result, industry standards for barcodes have been created to help insure that different scanners operating in different environments can read the same barcode.
Barcode verifiers capture an image of a barcode and analyze the barcode symbol according to test methods prescribed by the industry standards. The barcode verifiers can report the results of these tests and can alert an operator of problems.
The tests often prescribe sampling a barcode symbol at various locations in order to estimate a quality for the entire barcode symbol. For example a linear barcode, which has dark, variable-width barcode bars aligned in parallel and spaced by light, variable-width barcode spaces, may be sampled along parallel lines transverse to the barcode bar/spaces (i.e., along scan lines). Sampling the barcode in this way may cause the barcode verifier to miss certain printing errors that appear parallel to the scan lines. Printing errors of this sort may be common to many barcode printers.
Barcode printers typically use print heads to print a barcode. The print heads in ink jet printers, dot matrix printers, and thermal printers have a linear array of print elements (i.e., dots) to facilitate printing. Printed barcodes are printed dot-by-dot as paper is fed through the printer. When one print element becomes inoperative (e.g., clogged, stuck, burned-out, etc.) an unprinted line (i.e., gap) may appear in the printed barcode symbol. Since these unprinted lines are formed parallel to the test sampling lines (i.e., along the scan line direction), they may go unnoticed.
Therefore, a need exists for barcode verifier that can detect an unprinted line (or lines) in a barcode symbol along the scan line direction and generate a printer malfunction report.